Gas accelerating method and apparatus



Dec. 10, 1963 R. x. MEYER 3,113,427

GAS ACCELERATING METHOD AND APPARATUS Filed Nov. 25, 1959 3 Sheets-Sheet1 I00- 3 CESIUM\ 30- SODIUM E 560- 540- E B o x v HYDROGEN\ MAGNET E H6.3 ROTATION DIRECTION I l 0 5,000 new 15,000 '8 TEMPERATURE, DEGREESKELVIN- 8 FIG. 2

PLASMA 10 lb ROTATION DIRECTION FlG.5d FlG.5e

FREQUENCY THREE PHASE MULTIPLIER ALTERNATOR RUDOLF X. MEYER INVENTOR.

A TTOR/VE Y Dec. 10, 1963 R, x, MEYER 3,113,427

GAS ACCELERATING METHOD AND APPARATUS Filed Nov. 25, 1959 3 Sheets-Sheet2 THREE ,PHASE ALTERNATOR FR EQUENCY M U LTI PLI ER COOLANT FIG.6

THREE PHASE ALTERNATOR FREQUENCY MULTIPLIER A RUDOLF X. MEYER INVENTOR.

A 7' TORNE Y Dec. 10, 1963 R. x. MEYER GAS ACCELERATING METHOD ANDAPPARATUS Filed NOV. 25, 1959 FIG. IO

FIG. l4

MIXING [CHAMBER RUDOL F X. MEYER INVENTOR.

SEPARATION CHAMBER FIG. l5

4 TTOfP/VE) United States Patent 3,113,427 GAS ACCELERATHJG METHUD ANDAPPTUS Rudolf X. Meyer, Pacific Palisades, Calif., assignor to SpaceTechnology Laboratories, Inc, Pacific Palisades, (Ialifi, a corporationof Delaware Filed Nov. 25, 1959, Ser. No. 855,330 (Jlairns. (Cl.oil-35.5)

This invention relates generally to the art of magnetohydrodynamics,that is, the art treating the phenomena of motion of electricallyconductive fluids in the presence of magnetic fields. in particular, theinvention concerns improved methods and apparatus for obtaining andsustaining a high rotational speed of a gas without resort to rotatingmechanical elements.

In certain applications it is desirable to expose gases to a highcentrifugal force. If, for example, it is desired to separate a mixtureof gases into its constituents, a device capable of rotating the gasesat high speeds could be utilized. Such devices are generally calledcentrifuges. Since the actual force exerted on the constituents of themixture would be proportional not only to the mass of each constituentbut also to the square of its rotational velocity, the higher thevelocity the more efilcient the separation. If the molecular weights ofthe gases, and hence their masses, are relatively close in value, veryhigh speeds are required to obtain any useful degree of separation withan appreciable degree of yield rate.

The usual type of centrifuge is mechanical in nature. Stress limitationsimposed by the rotating mass of the structural assembly limits themaximum rotational speed obtainable to that equivalent to a tip speed ofthe order of 1000 feet per second. Such speeds have proven inadequatefor efiicient separation of gas mixtures, particularly where theconstituents of the mixture have molecular weights comparatively closein value.

Accordingly, it is an object of this invention to provide an improvedmethod and means for imparting high rotational speed to gases.

It is a further object to provide improved methods and means forobtaining sustained high rotational speeds of a gas without resort tothe use of rotating mechanical components.

The foregoing and related objects are realized, according to thisinvention, by inducing rotational motion in an electrically conductivegas (a plasma) by means of time varying magnetic fields. For example, achamber is filled with a plasma and a plurality of magnetic fieldgenerators are located around the outside of the chamber. These magneticfield generators are oriented to produce, Within the chamber, magneticfields that traverse the plasma. These generators are sequentiallyenergized and de-energized. This subjects the plasma to a rotatingmagnetic field. The eddy currents generated in the plasma by thisrotating magnetic field tend to drag the gas in the same direction asthe direction of rotation of the magnetic field. After a period of timethe rotational rate of the plasma will tend to approach the rotationalrate of the magnetic field.

In one embodiment, where it is desired to separate a mixture of ionizedgases into its constituents, the mixture is introduced into acylindrical chamber. The rotating magnetic field induces a highrotational rate of the mixture and the resulting centrifugal forcecauses the various constituents of the mixture to assume approximatelydiscrete annular layers around the axis of the chamber, therebyovercoming the natural tendency toward diffusion and mixing. Thedesired, separated constituents may be withdrawn by opening appropriategas exits positioned at difierent, radially separated end portions ofthe cylindrical chamber. This arrangement is useful, for example, inseparating an ionized, gaseous mixture into its constituents. V

In another embodiment, the arrangement of the invention is useful infission type nuclear reactor rocket engines. A gaseous fissionabiematerial is used for propellant heating without loss of fissionable'material from the engine system. In this embodiment the plasma subjectedto the cyclic magnetic field is the fissionable gas used to heat agaseous propellant. A rocket expansion nozzle is provided at one end ofa generally cylindrical rocket engine chamber and coaxial with thechamber axis. A propellant, such as hydrogen, is introduced into thechamber and is thoroughly mixed with the fissionable plasma, therebyraising the propellant temperature. The centrifugal force induced inthis mixture then tends to separate the fissionable material (plasma)from the propellant as the propellant flows toward the nozzle.Substantially complete separation takes place before the propellantenters the nozzle, where the propellant is allowed to expand through thenozzle to produce thrust in the conventional manner. The fissionableplasma is thus preserved from passage through the nozzle and isavailable for continual propellant heating within the chamber.

in the drawing, wherein like reference characters refer to likeelements:

PEG. 1 is a schematic representation of a typical ionized gas;

FIG. 2 is a plot of percent ionization versus temperature for a numberof gaseous materials;

FIG. 3 illustrates a rotating magnetic field superimposed upon acontainer of plasma;

FlG. 4 illustrates the apparatus associated with the operation of oneembodiment of this invention;

FIGS. 5a through 52 illustrate diiferent aspects of the current flow inthe magnetic field generators of the apparatus of H6. 4;

P16. 6 illustrates the apparatus of this invention as associated withthe separation of a mixture of ionized gases;

FIG. 7 is a sectional view of the apparatus of FIG. 6 taken in a planealong the line 77 thereof;

FIG. 8 illustrates the apparatus associated with the operation of thisinvention in the separation of a mixture of gases generally;

Phil. 9 illustrates aspects of operation of embodiments of the apparatusof this invention in measuring induced voltages;

P16. 10 is a graph illustrating the relationship of magnetic fieldrotational rate, plasma rotational rate, and in duced electromotiveforce, in apparatus of the invention;

FIG. 11 illustrates an embodiment of this invention as applied to anuclear fission rocket engine;

H6. 12 is a sectional view of the apparatus of FIG. 11 taken along theline 12-l2 thereof;

FlG. 13 illustrates an alternative embodiment of a nuclear fissionrocket engine according to this invention;

14 illustrates another alternating embodiment according to thisinvention, as embodied in a nuclear fission engine; and

FIG. 15 illustrates an embodiment of this invention as applied to aspace vehicle.

This invention is predicated upon the use of characteristics exhibitedby electrically conductive gas in the presence of magnetic fields toinduce very high rotational velocities in the gas. As will be explained,these velocities are considerably in excess of those attainable withmechanical type centrifuges.

For purposes of clarity the phenomena used in practicing the inventionwill be discussed prior to a detailed explanation of specificembodiments. Referring to FIG[ 1, there is illustrated a typicalelectrically conductive, ionized gas it hereinafter called a plasma. Theplasma 3 lit, for the purposes of this invention, may be ionized to anydegree and thus consists, basically, of three types of particles:negatively charged electrons lfla; positively charged ions or nucleilfib (with or without bound electrons); and neutral atoms or neutralsitlc. With increasing degrees of ionization of the plasma 19, thecharged particles {the electrons a and ions 1%) will increase in numberand the neutrals lldc will decrease in number.

The electrons 19a in PEG. 1 act as current carrying electrons in amanner analogous to the current carrying phenomena exhibited in theusual electrical conductor as, for example, a copper wire. Therefore, asthe degree of ionization of the plasma It) is increased, the electricalconductivity of the plasma 1% is increased. As is described below, thegreater the electrical conductivity of the plasma it), the moreefficient is the operation of apparatus of this invention.

The curve of PEG. 2 illustrates the percent ionization of variousgaseous materials as a function of temperature.

in some applications it is necessary to separate a mixture of gaseswherein the characteristics are such that very high temperatures wouldbe required to obtain an appreciable degree of ionization. Certainphysical limitations, such as chamber strength at very hightemperatures, may prohibit the operation at such temperatures. However,if some element such as cesium (which as shown in REG. 2 ionizes at alow temperature) is added to the mixture, an effective increase isrealized in the number of current carrying electrons in the mixture at acomparatively low temperature. This would give the same effect as thatrealized if the entire mixture had an appreciable degree of ionizationdue to high temperature operation. Operation in accordance with thisinvention may then be practiced upon this highly ionized mixture, andeffective separation of the mixture into its constituents can beachieved at this lower operating temperature. Such a technique isreferred to as seeding. Seeding is generally useful Whenever theeffective amount of ionization at a given temperature is to beincreased, as for example in fission reactors.

In the described embodiments of this invention, electrical currents areinduced in the gas by interaction of the gas with a changing magneticfiux. A non-changing magnetic flux can be incorporated in a system toinduce a rotation of the gas, but such a system requires the use ofelectrodes in direct contact with the gas to supply the requiredelectric currents. However, the effects of corrosion of the electrodesdue to high electric current densities and due to chemical reaction ofthe gas with the electrodes (for example, the corrosive effect ofuranium hexafiuoride on most materials) limits the useful life of suchan arrangement. This corrosive effect increases with increasing plasmatemperature, and thus this arrangement has a limited utility Wherecomparatively long operating times a thigh temperatures are required.

Therefore, if there are to be no electrodes in contact with the plasma,some arrangement must be utilized to induce the rotation of the plasmaby means purely external to the plasma.

The phenomena of inducing rotation in the electrically conductive plasmamay be better understood by reference to FIG. 3. This figure shows, inpictorial form, the forces acting to effect rotation of the plasma.Assume that a magnet 12 is being rotated counterclockwise about an axis13. A hollow, cylindrical plasma container 16 (of a magneticallytransparent material such as Pyrex glass) transmits magnetic flux M fromthe magnet 12 into the plasma 10. As the magnet 12 is rotated, itsmagnetic fiux 14 cuts through the plasma 10. Since the plasma 10 is aconductor, the free, current-carrying electrons in the plasma It) cancarry current; thus eddy currents 18 are induced in the plasma It) bythe rotating magnet 12. By Lenzs law, the direction of the forcedeveloped by interaction between these eddy currents 18 in the plasmaIt) and the magnetic flux l4 producing them will be such that the plasma19 tends to follow the same direction of rotation as that of the magnet12. (If we assume that the plasma ill rotated at the same speed as thatof the magnet 12, there would be no cutting of the magnetic flux 1 bythe plasma it and thus no eddy currents 13 would be produced. This wouldnot result in any induced force, and hence there could be no rotation ofthe plasma 1%.) Thus, there must be some relative motion between theplasma 19 and the magnet 12 in order to produce the eddy currents 18which result in the required rotational force.

The rotation of the plasma it), then, is in the same direction as thatof the magnet 12, only slower; the difference in rotational rate betweenthe magnet 12 and the plasma T19 is defined as the slip.

As will be discussed in connection with FIG. 4, it is possible to inducethe rotation in the plasma by producing only the effect of a mechanicalrotation of a magnet, instead of by actually rotating a permanentmagnet. FIG. 4 shows an arrangement according to this inventioncomprising a hollow cylindrical chamber 2t) surrounded by a plurality ofmagnetic field generators 22, which may be, for example, a plurality ofelectric windings. The chamber 28 is filled with a plasma 10. Themagnetic field generators 22 are oriented so that the magnetic flux 24generated by the magnetic field generators 22 traverses the chamber 20and passes through the plasma 10. The magnetic field generators 22 shownin this configuration are connected to an alternator 28, which, forexample, may be of the three-phase type. The magnetic flux 24- isrotated electrically by means of the three-phase current from thealternator 28, there being no mechanical rotation. The alternator 28 andmagnetic field generators 22 are interconnected in a mannerconventionally used in induction motors.

FIG. 5a shows, in schematic form, a typical magnetic field generatorarrangement. Twelve magnetic field generators 30 are shown connected soas to produce four magnetic poles when connected to a three-phasealternator. The magnetic flux 24 in FIG. 5a is shown at time 4 in FIG.5b. At this time 4 in FIG. 5b the current (l in a first magnetic fieldgenerator is at a positive maximum value; the current (l in a secondmagnetic field generator is at 50 percent of its maximum negative value;and the current (l in a third magnetic field generator is also at 50percent of its maximum negative value. Since the strength of themagnetic flux generated by an electrical current is proportional to themagnitude of the current, the magnetic flux 24 (shown schematically inFIG. 5a) represents the actual magnetic flux field strength and vectordirection. Similarly, FIGURES 5c, 5d, and 5e show schematically themagnetic flux at times corresponding to times 1, 2, and 3, respectively,of FIGURE 512.

As indicated in FIG. 5a, the magnetic poles (N and S) effectivelyrotate. When the magnetic field generators 22 of FIG. 4 are operated ina similar manner there is a rotation of the magnetic poles, the rotationbeing produced by the currents in the magnetic field generators 22-.This magnetic pole rotation, in turn, generates eddy currents within theplasma 10, with the free electrons Illa carrying the current. These eddycurrents, reacting with the magnetic flux 24, develop a force tending toproduce rotation of the entire plasma 10. Collisions between theelectrons 10a and nuclei 10b, and between the electrons and the neutralsof the plasma 10 result in a net rotation of the entire plasma in thesame direction as that of the electrons. Thus, with many electrons 10apresent in the plasma 10 (i.e., a high degree of ionization of theplasma 10), more collisions will take place and the eddy currents willbe stronger, resulting in a higher plasma rotational rate for a givenset of operating conditions.

The speed of plasma rotation is dependent upon both the frequency of thealternating current supplied to the magnetic field generators 22 andupon the number of poles. Since the speed of rotation of the magneticflux 24 (FIG.

4) is proportional to the frequency of the current for a fixed number ofpoles, a typical frequency multiplier 32 can be included in the circuit.This multiplier 32 will allow operation at high rotational speeds far inexcess of speeds obtainable with mechanical type centrifuges. As therotational speed is increased, the centrifugal force exerted on theplasma 1% increases. The entire plasma It) is thus subjected to a highcentrifugal force that can be sustained for virtually indefiniteperiods.

It will be appreciated that the particular orientation andinterconnection of the magnetic field generators 22 in FIG. 4 is onlyone of many possible arrangements that can be utilized to accomplish theresults of this invention. The basic requirement to be satisfied is thatthe rotating magnetic flux 24 traverses the plasma It in a directionsuch that the induced eddy currents interacting with the magnetic flux24 produce a net rotation of the plasma It).

An embodiment of this invention is shown in FIG. 6 wherein a separationof a mixture of plasmas into its constituents is accomplished. In thisembodiment a cylindrical chamber 40 is filled with a mixture of plasmas42 (this filling process may occur simultaneously with the gaswithdrawal to be described).

The magnetic field generators 22 are connected to a three-phasealternator 28 through a frequency multiplier 32. An end portion 40a ofthe chamber 40 is equipped with a plurality of radially spaced gas exits44, located at predetermined distances from the longitudinal axis of thechamber 40. A coolant supply system 46 is provided to maintain thechamber 40 at temperatures lower than that of the plasma mixture 42.Coolant material 48, for example water, is pumped through the annularspace formed by an outer cylinder 50 surrounding the chamber 40.

FIG. 7 shows a sectional view, along line 77, of the chamber 40 and theouter cylinder Sil of FIG. 6 during operation of the apparatus of FIG.6. When the magnetic field generators 22 are energized, the rotatingmagnetic flux 24- induces rotation of the plasma mixture 42. As highrotational speeds of the plasma mixture 42 are achieved, centrifugalforce will cause the heaviest particles to assume the form of an annularenvelope at the periphery of the chamber 48. The next heaviest particleswill assume an annular envelope of smaller radius than that of theheaviest particles. The lightest particles will assume a position atmore central regions of the chamber 40. Since the actual force exertedon each individual particle is proportional to the square of itsrotational velocity, even particles whose atomic mass values arecomparatively close are effectively separated at the very highrotational speeds achieved by the embodiment of this invention.

The electrons in the mixture 42, even though the lightest particles inweight, generally will not exclusively occupy the center portion of thechamber 40. The electrostatic forces existing between the negativelycharged electrons and the positively charged nuclei are so intense thatthe plasma mixture will tend towards electrical neutrality in any givenunit volume.

The gas exits 44 (FIG. 6) may be individually or simultaneously openedto withdraw the contents of the chamber 4-0. The positions of the exitsat the end portion 40a of the chamber 40 were selected so as to becoincident with the annular layers assumed by the particles.

It will be appreciated that the greater the rotational rate, the greaterwill be the maximum gas withdrawal rate (yield). Since the constituentsof a mixture of gases have a natural tendency to diffuse, the rotationalrate must be sufficient so that the centrifugal force overcomes thisdiifusion. Also, when a mixture of gases is moving at an appreciablevelocity there is a tendency for turbulent mixing of the constituents ofthe mixture. Thus, high rotational rates are required to provideseparation of the constituents so that the yield and purity of the yieldmay be maximized.

In many applications, operational temperature limits on the chamberprohibit sustained operation at a temperature sutficient to ionize eachconstituent of a gas mixture. The teachings of this invention can alsobe utilized to eitect an efficient separation of such a gas mixture.This embodiment is illustrated in FIG. 8 wherein a chamber 44 is filledwith a gas mixture 60 that is to be separated into its constituents. Agas 62 that ionizes at low temperatures, such as cesium, is introducedinto the chamber 40 along with the other difiicult-to-ionize material tobe separated. The magnetic field generators 22 are connected as shown inFIG. 5 and operated through an alternator 28 and frequency multiplier 32as shown in FIG. 8. The rotating magnetic flux 24 induces rotation inthe cesium plasma within the chamber 49, which, in turn, causes rotationof the entire gas mixture. The centrifugal force associated with thisrotation effectively separates the gas mixture into its constituents.The gas exits 44 on the chamber end portion 40a are opened to permitwithdrawal of the separate constituents of the gas mixture, and thecesium portion of the mixture may either be allowed to remain in thechamber or be reintroduced along with new material to be separated intoits constituents.

From the foregoing it is seen that substantially any gaseous materialsmay be separated from each other if the materials diiier in molecularweight (or at molecule disassociation temperatures, atomic weight).Thus, even materials that diifer in atomic weight by relatively smallamounts, say uranium 235 and uranium 238, may be advantageouslyseparated through the use of arrangements of the invention. In the caseof uranium, the materials may be in the form of a normally gaseouscompound, say uranium hexafiuoride.

In the operation of embodiments of this invention it is seen that thereis a relative motion between a conductor (the plasma) and the magneticflux. Therefore, there will be a back electromotive force induced in themagnetic flux generators. For a given current characteristic the backelectromotive force induced in the magnetic field generators 22 of FIG.9 will be a maximum when the relative motion between the generators 22and the'plasma it is a maximum. This condition occurs in any embodimentof this invention during the existence of starting transients whenoperation is initiated. The minimum back electromotive force induced inthe magnetic field generators 22 occurs when the plasma 10 reaches itsmaximum speed.

This back electromotive force characteristic, being a function of therotational speed of the plasma iii, can be used as a control system tomonitor and regulate the centrifugal force applied to the plasma. FIG.10 illustrates graphically the relationship between the backelectromotive force induced in the magnetic field generators 22, therotational speed of the plasma lit, and the rotational speed of themagnetic field generators 22. A voltage sensing means 76 (Flu. 9) can beused to measure this back electromotive force. The value of theelectromotive force indicates the rotational speed actually obtained bythe plasma it). This sensing means '78, as shown in PEG. 9, can beconnected to control the current supplied to the field generators 22 bythe alternator 28.

The curve 61 of FIG. 10 starts at a zero value and rises to a peakduring the starting transient, and then decreases to a low value as theplasma rotational rate 63 increases to its maximum value (after themagnetic field generator rotational rate 6? reaches its steady-statevalue). it will be appreciated that as the plasma is withdrawn from thechamber, the slip between the plasma rotational rate and the magneticfield rotational rate will increase. This is shown by curve 65 whichindicates the plasma rotational rate during withdrawal of the plasmafrom the chamber. Since the slip is increasing, the inducedelectromotive force will also increase as shown by curve 67. Thus thevoltage 7 sensing means 7:) of FIG. 9 indicates the amount of plasmawithdrawn as well as plasma. rotational speed.

The inducement of a high rotational velocity of a pin..-

is utilized in another embodiment of this invention shown in FIG. ll.This embodiment is a fissionable gas rocket propulsion engine. Thecylindrical chamber 86 contains a fissionable gas 82, for example hightemperature uranium hexaliuoride undergoing fission, which under theseconditions is a plasma. One end portion Stu of the chamber St isequipped with a nozzle 84 located on the center line of the chamber 8%.A propellant 96, for example hydrogen, is introduced from a storage tank95 into the chamber 8% at some distance axially of the nozzle ea.intimate contact and mixing of the propellant 99 with the uraniumhexofluoride plasma 32 results in a heating of the propellant toapproximately the temperature of the plasma 32. At this temperature thepropellant itself may become a plasma and thus add to the eilhcncy ofoperation. When the magnetic field generators 22 (FIG. 12) are operatedto produce a rotating magnetic f i 24 the eddy currents generated in theplasma 2E2, reacting with the rotating magnetic flux 2 induce a rotationof the plasma $2. Collisions between the plasma 82 and the propellant 90results in a high rotational rate of both the plasma 82 and thepropellant 9d. The heavier plasma 82 will be forced to thecircumferential periphery of the chamber in the form of an annularblanket and the lighter propellant 9 will then occupy the central, axialregions of the interior of the cylindrical chamber Sil.

The propellant 99 (FIG. 11) then passes through the nozzle 84-,expanding and producing thrust in the convenional manner of rocketpropulsion engines. The plasma 82, held at the periphery of the chamber8%, does not escape and is thereby conserved within the chamber 89.

The propellant 9% may also be utilized as a coolant prior tointroduction into the chamber 39, as shown in FIG. 13. This isaccomplished by regenerative cooling of the chamber Si wherein thepropellant 99 passes through an annular jacket 94 surrounding thechamber 3i) as the propellant 9t flows from the propellant storage tank96 to the chamber 8t If the propellant 90 is introduced into the chamber8i from locations circumferential of the chamber (as illustrated in FlG.13) the propellant will be urged into more intimate mixing with thelissioning gas during its journey toward the axis of the chamber.

In order to reduce the weight and bulk of the apparatus, the wallsdefining the chamber Sti may be made of a high elficiency neutronreflector material, such as beryllium. The chamber 39 becomes, then,both a neutron reflector and a moderator for controlling the criticalreaction of the fissioning gas. Furthermore, a neutron reflectingmaterial that may easily take a gaseous form, such as lithium, may beadded to the chamber in order to even further reduce the requireddimensions of the gaseous fission reactor. Since lithium is intermediatein atomic weight between hydrogen and uranium, the lithium will inoperation form an annular blanket inside of the annular uranium regionsof the uranium blanket. Of course, the lithium can be used as apropellant too.

Seeding the plasma 82 with a material such as cesium may be utilized tofurther enhance the operation of the apparatus.

Solid fuel elements 98 (FIG. 14) may be included within the chamber 88.These elements $8 may be also regeneratively cooled by the propellant 9iand reduce the bulk of the engine even further by improving neutroneconomy and providing an additional measure of propellant 9i)preheating.

Operation of the propulsion engine embodiments of this invention isindependent of whether the fissionable gas or the propellant (or both)is the plasma. Thus, for example, the fissionable gas may be effectivelya non-plasma at the selected operating tem erature, but with thepropellant plasma at the same selected operating temperature. in thisvariation the magnetic field gen aters will induce a rotation in theplasma propellant which, in turn, will cause the non-pl: sma fissionablcgas to rotate. However, due to the difference in molecular weights, thelighter ropellant will still occupy axial regions of the chamber and theheavier fission-able gas will occupy circumlereiv tial regions of thechamber.

Gas temperatures in regions of the chamber may even exceed the meltingpoint temperature of the Walls defining the fission reaction chamber.The reason for this is that the heat is produced in regions spaced fromthe walls of the chamber, and the transpiration effect of introducingthe cool propellant gas into the chamber through its walls cools thewalls. Thus specific impulses of appreciably more than 1000 may beobtained. it is to be further noted hat the walls may be preserved fromthe full heating cliects of the fission reaction by establishinglocalized additional magnetic fields (not shown) in regions adjacent tothe inner surfaces of the walls. These local' ic fields are orientedwith respect to the rota-. g a known manner such that the interaction(of the moving plasma charges and the magnetic field) produces aresultant force on the plasma urging it away from the walls.

it will be appreciated that While in FIGS. ll through 14 only onereaction chamber 3:; is shown (both the mixing of the propellant withplasma and their ultimate separation rior to expansion through thenozzle 84, being eiiected in the same chamber), other arrangements canalso be utilized. For example, FIG. 15 shows variation wherein a mixingchamber llrid is physically separated from a separation chamber Hi2. Thetwo chambers are interconnected by a duct 1&6 which is alsoregenerativcly cooled by the propellant 90. Such an arrangement may bepreferred, for example, in a space vehicle 119. A pump M8 and lines 112are also provided in this embodiment for returning the fissionable gasmaterial back to the mixing chamber ltd-"Ii from the separation chamberHi2.

From the foregoing, it is seen that this invention not only provides animproved method and apparatus for inducing very high rotational speedsin gases, but does so without resort to rotating mechanical componentsand thus allows the realization of rotational velocities free ofmechanical stress considerations.

What is claimed is:

1. A gas accelerating apparatus of the kind capable of accelerating aplasma comprising, in combination: a chamber having walls defining acavity adapted to contain a plasma to be accelerated; and cyclicmagnetic field generating means oriented, with respect to said chamber,to subject the plasma to a cyclic magnetic field thereby to exert aforce on said plasma inducing a rotation of said plasma within saidcavity.

2. The gas accelerating apparatus defined in claim 1 wherein saidapparatus further includes a voltage measuring means connected to saidcyclic magnetic field generating means to measure voltage induced insaid generating means by the relative motion of said generating meanswith respect to said plasma, thereby to provide information relative tothe rotational velocity of the plasma.

3. The gas accelerating apparatus defined in claim 1, further includingpolyphase alternating current generating means, and wherein saidmagnetic field generating means is connected to be powered by the outputof the polyphase alternating current generator means.

4. The gas accelerating apparatus defined in claim 3, further includingfrequency multiplier means connected between the polyphase alternatingcurrent generating means and the magnetic field generating means.

5. Gas accelerating apparatus of the type capable of accelerating amixture of plasmas made up of constituents having at least two diiferentmasses, and of selectively separating said constituents according totheir masses, comprising, in combination: a chamber having wallsdefining a cavity and adapted to confine the mixture of plasmas withinthe cavity; cyclic magnetic field generating means oriented to subjectsaid mixture of plasmas to a cyclic magnetic field thereby to exert aforce on said mixture of plasmas to efiect a rotation of said plasmaswithin 7 said chamber; and means coupled to said cavity to selectivelyextract at least some portions of said mixture of plasmas according totheir masses.

6. Gas accelerating apparatus of the type capable of accelerating amixture of plasmas made up of constituents having at least two differentmasses, and of selectively separating the mixture according to themasses of the constituents, comprising, in combination: an elongatedinner chamber having Walls defining a cavity adapted to confine thereina mixture of plasmas to be accelerated; an outer chamber around saidinner chamber and having walls defining an annular cavity between saidouter and inner chambers; said annular cavity adapted to circulate acooling medium between the inner side of said outer chamber and theouter side of said inner chamber; coolant connection means connected topass the cooling medium into said inner chamber from regions spaced fromthe long axis of said chamber; magnetic field generating means orientedso to subject the plasma mixture Within the inner chamber cavity to acyclic magnetic field, thereby to exert a force on said plasma mixtureinducing a rotation of said plasma mixture within said inner chamber;and means coupled to said cavity to selectively extract at least aportion of the said constituents of said plasma mixture according totheir masses.

7. The gas accelerating apparatus defined in claim 6 wherein saidmagnetic field generating means is adapted to receive polyphasealternating current; and said apparatus further includes alternatingcurrent generating means adapted to generate polyphase alternatingcurrent, frequency multiplying means connected to receive and multiplythe frequency of said polyphase alternating current generated by saidalternating current generating means, said frequency multiplierconnected to transmit said multiplied frequency polyphase alternatingcurrent to said magnetic field generating means, and voltage measuringmeans 10 coupled to said magnetic field generating means to measureinduced voltages therein.

8. Gas separation method, comprising the steps of: injecting a mixtureof different isotopes into a chamber; ionizing at least a portion ofsaid mixture; establishing a rotating magnetic field in regionscontaining said isotope mixture, thereby inducing a rotation of saidisotope mixture; and selectively extracting the constituents of saidisotope mixture.

9. A gas separation method comprising the steps of: injecting a mixtureof plasmas into a chamber; establishing a rotating magnetic field inregions containing said plasma mixture thereby inducing rotation of saidplasma mixture; simultaneously and continually measuring an induced backelectromotive force produced by interaction of the field and the plasma;sustaining said rotating magnetic field until after the induced backelectromotive force is at a minimum; and simultaneously and selectivelyextracting the constituents of said plasma mixture.

10. A gas separation method, comprising the steps of: injecting a gasmixture into a chamber; injecting a plasma into the same chamber;establishing a rotating magnetic field in regions containing said gasmixture and said plasma thereby inducing a rotation of said plasma forinducing a rotation of said gas mixture; sustaining said rotatingmagnetic field while simultaneously and selectively extracting theconstituents of said gas mixture.

References Cited in the file of this patent UNITED STATES PATENTS2,798,181 Foster July 2, 1957 2,819,423 Clark Jan. 7, 1958 2,850,662Gilruth et a1. Sept. 2, 1958 2,894,891 Grebe July 14, 1959 2,917,443Grebe Dec. 15, 1959 2,919,370 Giannini Dec. 29, 1959 2,929,952 GianniniMar. 22, 1960 2,932,797 Symon Apr. 12, 1960 2,960,614 Mallinckrodt Nov.15, 1960

6. GAS ACCELERATING APPARATUS OF THE TYPE CAPABLE OF ACCELERATING AMIXTURE OF PLASMAS MADE UP OF CONSTITUENTS HAVING AT LEAST TWO DIFFERENTMASSES, AND OF SELECTIVELY SEPARATING THE MIXTURE ACCORDING TO THEMASSES OF THE CONSTITUENTS, COMPRISING, IN COMBINATION: AN ELONGATEDINNER CHAMBER HAVING WALLS DEFINING A CAVITY ADAPTED TO CONFINE THEREINA MIXTURE OF PLASMAS TO BE ACCELERATED; AN OUTER CHAMBER AROUND SAIDINNER CHAMBER AND HAVING WALLS DEFINING AN ANNULAR CAVITY BETWEEN SAIDOUTER AND INNER CHAMBERS; SAID ANNULAR CAVITY ADAPTED TO CIRCULATE ACOOLING MEDIUM BETWEEN THE INNER SIDE OF SAID OUTER CHAMBER AND THEOUTER SIDE OF SAID INNER CHAMBER; COOLANT CONNECTION MEANS CONNECTED TOPASS THE COOLING MEDIUM INTO SAID INNER CHAMBER FROM REGIONS SPACED FROMTHE LONG AXIS OF SAID CHAMBER; MAGNETIC FIELD GENERATING MEANS ORIENTEDSO TO SUBJECT THE PLASMA MIXTURE WITHIN THE INNER CHAMBER CAVITY TO ACYCLIC MAGNETIC FIELD, THEREBY TO EXERT A FORCE ON SAID PLASMA MIXTUREINDUCING A ROTATION OF SAID PLASMA MIXTURE WITHIN SAID INNER CHAMBER;AND MEANS COUPLED TO SAID CAVITY TO SELECTIVELY EXTRACT AT LEAST APORTION OF THE SAID CONSTITUENTS OF SAID PLASMA MIXTURE ACCORDING TOTHEIR MASSES.